Many sentences in English have more than one clause. (A clause is a group of words containing a subject and a verb.) When you have two clauses in an English sentence, you must connect the two clauses correctly. One way to connect two clauses is to use and, but, or, or so between the clauses.
(Indonesian Version)

The sun was shining and the sky was blue.

The sky was blue, but it was very cold.

It may rain tonight, or it may be clear.

It was raining outside, so I took my umbrella.

In each of these examples, there are two clauses that are correctly joined with a coordinate connector—and, but, or, or so—and a comma (,).

The following example shows how this sentence pattern could be tested in the Structure section of the TOEFL test.

Example

I forgot my coat, ____ I got very cold.

(A) then
(B) so
(C) later
(D) as a result

In this example, you should notice quickly that there are two clauses, I forgot my coat and I got very cold. This sentence needs a connector to join the two clauses. Then, later, and as a result are not connectors, so answers (A), (C), and (D) are not correct. The best answer is answer (B) because so can connect two clauses in this manner.

The following chart lists the coordinate connectors and the sentence pattern used with them.

EXERCISE 5: Each of the following sentences contains more than one clause. Underline the subjects once and the verbs twice. Circle the connectors. Then indicate if the sentences are correct ‘(C) or incorrect (I).

1. The lawn needs water every day, or it will turn brown. (C)

Analysis:

Both clauses are correct and coordinate connector is correct.

2. The book was not long, it difficult to read. (I)

Analysis:

Second clause should be it is difficult to read. There is not coordinate connector.

3. It was raining, so decided not to go camping. (I)

Analysis:

Second clause has no Subject.

4. The material has been cut, and the pieces have been sewn together. (C)

Analysis:

Both clauses are correct and coordinate connector is correct too.

5. The patient took all the medicine, he did not feel much better. (I)

Analysis:

Both clauses are correct but there is no coordinate connector

6. The bill must be paid immediately, or the electricity will be turned off. (C)

Analysis:

Both clauses are correct and coordinate connector is correct, too

7. The furnace broke so the house got quite cold. (I)

Analysis:

Both clauses are correct, but there is no comma.

It should be The furnace broke, so the house got quite cold.

8. The dress did not cost too much, but the quality it seemed excellent. (I)

Analysis:

Second clause has two subject; the quality and it. It should be the quality seemed excellent.

Coordinate connector is correct.

9. The leaves kept falling off the trees, and the boys kept raking them up, but the yard was still covered. (C)

Analysis:

All clauses and coordinate are connectors correct, too.

10. The mail carrier has already delivered the mail, so the letter is not going to arrive today, it probably will arrive tomorrow. (I)

Analysis:

All clauses are correct, but coordinate connector So is wrong. So should be changed with but.